1. Technical Field
The present invention is directed toward a bench tester for a camshaft, and more particularly toward an apparatus for simulating the operating environment of a camshaft.
2. Background Art
Camshafts consist of a shaft having a plurality of axially spaced lobes or cams. In use in an internal combustion engine, the camshaft actuates valves of the engine during the combustion cycle. A persistent problem with camshafts, particularly camshafts used in high stress environments, such as NASCAR engines, is premature failure of the camshafts. The problem is exacerbated by camshafts having aggressive lobe designs intended to improve engine efficiency. The aggressive lobe design has increased the failure of camshafts. In addition, higher valve spring pressures are required to maintain valve lifter contact in camshafts having the aggressive lobe design. These increased valve pressures further contribute to camshaft failure. Not only can premature failure end a driver's attempt at winning or competing in a race, failure of the camshaft can render serious injury to expensive, high performance engines. While there are a number of ways to physically inspect a camshaft, these inspection techniques fail to identify all camshafts which will actually fail under operating conditions.
Prior to the advent of camshafts having aggressive lobe design and engines having increased valve spring pressure, testing the camshaft using low pressure valve springs at 2000 RPM for 30 minutes was considered a sufficient "break in" period to insure the camshaft would not fail prematurely. However, with current camshafts featuring an aggressive lobe design this traditional testing and "break in" technique has been found inadequate in anticipating extreme cam or lobe wear.
Experience has shown that if a camshaft is going to fail, it typically does so within the first couple of hours of use. To date, this use could only come from actually deploying the camshaft in a high revolution engine such as a NASCAR engine. However, because as discussed above, failure of the camshaft can cause serious injury to an engine, this method of testing camshafts is both cumbersome and potentially very expensive.
The present invention is directed toward overcoming one or more of the problems discussed above.